Question

A sulphide of Fe contains 46 5% of Fe by weight. Find the empirical formula of the sulphide
(Atomic weight S = 32. Fe = 56)​

Answer 1

Explanation:

A sulphide of iron contains 46.5% of iron by weight.

100 g of sample will contain 46.5 g of iron and 100−46.5=53.5 g of sulphur.

The atomic masses of iron and sulphur are 55.8 g/mol and 32.1 g/mol.

The number of moles of iron =

55.8g/mol

46.5g

=0.8333.

The number of moles of sulphur =

32.1g/mol

53.5g

=1.667

The ratio of the number of moles of iron to the number of moles of sulphur =0.8333:1.667=1:2

Hence, the empirical formula of the sulphide is FeS

2

.